This invention relates to a tire component, more particularly, novel bead-apex subassembly and a method of employing the bead-apex subassembly into a tire carcass.
The manufacture of tires involves numerous components and requires applying these tire components in a somewhat ordered sequence to form an assembly of components known as a xe2x80x9ctire carcassxe2x80x9d to which a belt package and a rubber tread is applied to make a green tire which is then vulcanized to finish the produce we commonly refer to as a xe2x80x9ctirexe2x80x9d.
The assembly of tire components, specifically a tubeless type tire, include a liner which forms an air impervious barrier to contain the air under pressure in the air chamber of a pneumatic tire, one or more plies reinforced by cords, a chaffer compound applied in two strips, two annular bead cores and a pair of apexes which are also generally applied in strips. The bead cores generally are applied over the chaffers. Other components such as sidewall strips, run-flat inserts, shoulder gum strips, and fabric toe guards can also be applied to form the tire carcass.
This stage of the tire building process is commonly referred to as the xe2x80x9cfirst stagexe2x80x9d of the tire building process. The components are applied over a cylindrical building drum that usually includes turn-up bladders and a center bladder to convert the subassembly of tire components from a cylindrical shape to a toroidal shape.
All or almost all the rubber components are usually applied to the building drum in strips. Each strip is wound onto the drum generally requiring a 360xc2x0 revolution, the ends of the strip are then spliced together.
To make the assembly process more efficient, it is desirable to preassemble many of these tire component strips. In U.S. Pat. No. 5,762,740 a method of laminating several of the components into a subassembly of carcass components is taught. This greatly improves the efficiency of the first stage building process.
The bead and apex have also been combined in a subassembly as is taught in U.S. Pat. No. 4,933,034. The apex is applied in a strip outwardly extending from the radially outer or peripheral surface of the annular bead core and then stitched at the ends of the strip. These components, once reassembled, must be stored in such a way that the apex is not damaged when it is subsequently brought to the first stage tire building machine.
Such prior art subassemblies of an apex strip to a bead core have the apex radially extending in a manner that requires the carcass to be inflated in the central region to bring the apex into contact with the carcass. After the carcass is inflated, a turn-up of the ply ends and the sidewall rubber is made in a step commonly referred to as the xe2x80x9cinflated turn-upxe2x80x9d. This sequencing of forming the carcass requires a more complex method of manufacturing the carcass because the components and subassemblies are not applied to the tire building drum in a flat state.
An object of the present invention is to avoid or eliminate the storage problems found in making a bead-apex subassembly.
Another object of the invention is to permit the carcass to be built with a bead-apex subassembly without requiring an inflated turn-up.
Another object of the invention is to build the bead apex subassembly at, but not on the first stage building drum, as the carcass is being constructed.
The present invention method of making a tire carcass (10) at a first stage tire building machine (100) has the steps of: a) cylindrically forming one or more strips of tire components (20, 40, 50, 60, 70) around a first stage tire building drum (5), the first stage tire building drum (5) having an axis of rotation; b) forming two annular bead-apex subassemblies (2) at a location in proximity to and spaced from the building drum (5), the subassemblies (2) being formed by applying an elastomeric apex strip (30) to a peripheral or radially outer surface (12A) of an annular bead core (12) having an axis of rotation; c) aligning the axis of rotation of each bead-apex subassembly (2) with the axis of rotation of the tire building drum (5); d) transferring each bead-apex subassembly (2) onto the tire building drum (5); e) applying any additional tire components (20, 40, 50, 60, 70) to form the tire carcass (10) prior to toroidally shaping the carcass (10). Preferably, the step of forming the two bead-apex subassemblies (2) occurs simultaneously with the cylindrically forming the carcass. (10).
In the preferred method, the step of forming two annular bead-apex subassemblies (2) further includes the steps of placing each bead core (12) on a rotatable support (80) in proximity to but separated from the tire building drum (5) and applying one elastomeric apex strip (30) onto a radially outer surface (12A) of each bead core (12) as the support (80) is rotated. Most preferably, the step of applying one elastomeric strip (30) to each bead core (12) includes the step of orienting the elastomeric apex strip (30) parallel to the axis of the bead core (12) relative to the width (W) of the strip. The step of applying one elastomeric. strip (30) to each bead core (12) includes the steps of stitching the apex (30) to the bead core (12), splicing ends (30A, 30B) of the apex (30) to form the annular bead-apex subassembly (2).
The step of aligning the bead-apex subassembly (2) axis with the tire building drum (5) axis further includes the steps of moving the support (80) to axially align the bead-apex subassembly (2) with tire building drum (5) axis.
The step of transferring the bead-apex subassembly (2) further includes the steps of removing the annular bead-apex subassembly (2) from the support (80) while maintaining axial alignment with the tire building drum (5), moving the support (80) to a location spaced from the tire building drum (5) and moving each bead-apex subassembly (2) onto the tire building drum (5).
The method of forming an annular bead-apex subassembly (2) as an intermediate article of manufacture to be used at a first stage tire building machine (100), the method comprising the steps of: a) placing an annular bead core (12) on to a support (80), the bead core (12) having an axis of rotation; b) applying an elastomeric strip of apex (30) onto a radially outer surface (12A) of the bead core (12), the strip (30) being applied with the width (W) of the strip (30) being oriented parallel to the axis of the bead core (12); c) stitching the strip (30) to the bead core (30); and d) splicing ends (30A, 30B) of the strips (30), thus, forming the annular bead-apex subassembly (2) as an intermediate article of manufacture to be used at a first stage tire building machine (100).
The resultant methods can yield a bead-apex subassembly (2) as an intermediate article of manufacture having an annular bead core (12) having a radially outer surface (12A); and an elastomeric strip of apex (30) affixed to the radially outer surface (12A) of the bead core (12) at a first end (31) of the strip (30) along a radially inner surface (33), the distances between the first end (31) and a second end (32), defining the width (W) of the strip (30), the width (W) of the strip (30) being substantially oriented parallel to the axis of the bead core (12) along the radially inner surface (33).